fix(performance): check if root_disk is valid and scheduler path exists before writing

lib/performance.sh

@@ -45,6 +45,7 @@ EOF
     local disk_type=$(lsblk -d -o name,rota | awk 'NR>1 {if($2==0) print "ssd"; else print "hdd"; exit}')
     local root_disk=$(lsblk -no pkname $(findmnt -n -o source /) | head -n1)
     
+    if [[ -n "$root_disk" ]] && [[ -w "/sys/block/$root_disk/queue/scheduler" ]]; then
         if [[ "$disk_type" == "ssd" ]]; then
             echo "mq-deadline" | sudo tee "/sys/block/$root_disk/queue/scheduler" > /dev/null
             log_info "Optimized I/O scheduler for SSD"
@@ -52,6 +53,9 @@ EOF
             echo "bfq" | sudo tee "/sys/block/$root_disk/queue/scheduler" > /dev/null
             log_info "Optimized I/O scheduler for HDD"
         fi
+    else
+        log_warning "Could not determine or access root disk scheduler. Skipping I/O optimization."
+    fi
     
     # Create performance monitoring script
     create_performance_monitor